Tape is a known medium or media for the storage of audio, video, and computer information. The information is typically written to and read from the tape magnetically and/or optically. Such tapes are available spooled on individual hubs and in single or dual hub tape cassettes/cartridges. The tape path for any type of tape cartridge and tape drive includes a tape head in close proximity to the tape. Many tape cartridges include an opening through which a tape head from a tape drive is inserted. The tape in a single hub tape cartridge also has an opening through which tape passes. The tape is accessed through the opening and then mechanically threaded through an external tape path and spooled onto a take-up hub after insertion into a tape drive device. The tape head has one or more transducer elements for writing to and/or reading from the tape.
Cassettes or cartridges including tape are commonly used to back up computer information from all types of computer systems. In work environments, tape is used to back up data or information on a regular basis. Tape and tape cartridges store vast amounts of data. In some instances, tape cartridges are used in a library which includes a tape drive coupled with a picking mechanism and a storage area for storing a number of tape cartridges. The tape cartridges in the storage area are accessible by the picking mechanism. The picking mechanism is controlled so that the picking mechanism picks a selected tape cartridge from it.sup.L F particular position in the storage area, and inserts the tape cartridge into the tape drive when the information on the particular tape cartridge is requested. The picking mechanism removes the tape cartridges from the tape drives and returns them to the storage area when the information is no longer needed.
When analyzing the different digital recording cartridges on the market, all have advantages and weaknesses. In general, there are two types of tape cartridges--the tape cartridge with a single hub and the tape cartridge with a double hub. The single hub cartridges have good capacities and low price, but have longer access times. In other words, it takes longer to get to the data than with a center park two hub cartridge.
In tape libraries, two hub cartridges with center park are preferred for their superior access time performance. Two hub cartridges which are center parked have better access time to data but have very little volume of the cartridge devoted to tape and therefore are less efficient in terms of using space. Two hub cartridges have either half the length of tape on one hub and the other half of the tape on the other hub in a two hub cartridge; or the full tape on one hub with the other hub empty; or portions of the tape of the full tape on one hub and portions of the full tape on the other hub. In this manner, the data is, at most, half the length of the tape away from its center parked position. The volume of tape compared to the volume of the cartridge is low since there are generally tape guides and other pins for providing a tape path within the cartridge. The additional pins and tape guides provide tape tracking but add to the cost of the cartridge and to the complexity of manufacture. Since each hub must have the capacity to hold the entire length of tape within the two hub cartridge on each of the hubs, tape capacity is lost since each hub is not filled with tape. In other words, each hub must have capacity in the event the entire tape is shuttled to one or the other of the hubs. The result is that a small percentage of the volume of the cartridge is tape. Generally, the volume of the cartridge devoted to tape is in the range of 7% to 10% of the total volume of the cartridge. Newer style, center park cartridges are generally costly. The many parts required add to the complexity of manufacture of the cartridges.
The recording capacity per cartridge is becoming increasingly important especially in tape library systems. As a result, there is a need for a two hub cartridge which can be center parked so that access to data is short. In addition, there is a need for a two hub cartridge which can hold a high volume of tape so that volumetric efficiency of the tape cartridge and the tape library which uses such a cartridge can be increased. In addition, there is a need for a cartridge which is easy to manufacture and which can be made inexpensively.